SEW电机抱闸调整及间隙数据

11.3Principles of the SEW brake 1.3.1Principles of project planning The SEW brake is a DC-operated electromagnetic disc brake with a DC coil which is opened electri-cally and braked using spring force. The system satisfies fundamental safety requirements: the brake is applied if the power fails.The principal parts of the brake system are the brake coil itself (accelerator coil + coil section =holding coil), consisting of the brake coil body (9) with an encapsulated winding and a tap (8), the moving pressure plate (6), the brake springs (7), the brake disc (1) and the brake bearing end shield (2).The significant feature of SEW brakes is their very short length: the brake bearing end shield is a part of both the motor and the brake. The integrated construction of the SEW brake motor permits particularly compact and sturdy solutions.00871AXX Fig. 1: Block diagram of the brake 1Brake disc 2Brake bearing end shield 3Carrier 4Spring force 5Working air gap 6Pressure plate 7Brake spring 8Brake coil 9 Brake coil body 10Motor shaft 11 Electromagnetic force 511109876321411.3.2Basic functionIn contrast to other DC-operated disc brakes, SEW brakes operate with a two coil system. The pressure plate is forced against the brake disc by the brake springs when the electromagnet is de-energized. The motor is braked. The number and type of the brake springs determine the braking torque.When the brake coil is connected to the appropriate DC voltage, the spring force (4) is overcome by magnetic force (11), thereby bringing the pressure plate into contact with the brake coil body.The brake disc moves clear and the rotor can turn.Particularly short response times When switching on:A special brake control system ensures that only the accelerator coil is switched on first followed by the holding coil (entire coil). The powerful impulse magnetization (high acceleration current) of the accelerator coil produces an especially short response time, particularly in large brakes, with-out however reaching the saturation limit (→ Fig. 2). The brake disc moves clear very swiftly and the motor starts up with hardly any braking losses.00868AENFig. 2: Functional principles of the two coil brake BS Accelerator coil 1) Brake I BAcceleration currentTS Coil section 2) Brake control system I H Holding current BS + TS = Holding coil M 3TSBS1)2)V AC01873AEN120msI BtI HAcceleration Holding1The particularly rapid response times of SEW brakes add up to a shorter motor startup time, mini-mum startup heating and therefore less energy consumption and negligible brake wear during startup (→ Fig. 3). These factors pay dividends to the user in the form of an extremely high starting frequency and long brake service life.00869AXX Fig. 3: Shortening the motor startup time with the SEW brake system The system switches over to the holding coil electronically as soon as the SEW brake has released.The braking magnet is now only sufficiently magnetized (with a small holding current) to ensure that the pressure plate is held in the startup position with adequate security and with minimum brake heating (→ Fig. 2).I S Coil current M B Braking torque n Speed t 1Brake response time 1)Switch-on procedure for operation with a rectifier without switching electron-ics 2)Switch-on procedure for operation with SEW rectifier with switching electronics, e.g. BGE (standard from size 112 upwards)t 1t 1t t t t t t I S I S M B M B n n 1)2)1When switching off:This means de-excitation occurs very rapidly when the coil is switched off, so the brake is applied with an extremely rapid reaction time, particularly with large brakes. This offers benefits to the user in the form of an especially short braking distance with a high repeat accuracy and high level of security, e.g. for applications involving drive units for vertical motion.00872AXXFig. 4: Shortening the braking distance by brake cut-off in the DC and AC circuitsThe response time for application of the brake is also dependent on how rapidly the energy stored in the brake coil can be dissipated when the electrical power is switched off. A free-wheeling diode is used for dissipating the energy for a “cut-off in the AC circuit”. The current decays according to an e-function.The current decays much more rapidly via the varistor when the DC circuit of the coil is interrupted at the same time, giving “cut-off in the DC and AC circuits”. The response time is significantly shorter (→ Fig. 4, Fig. 5). Conventionally, “cut-off in the DC and AC circuits” is implemented using an additional contact on the brake contactor (suitable for DC switching).Under certain circumstances, it is beneficial to use the electronic relays SR and UR (→ Sec.2.2.2.2) for interrupting the DC circuit.I S Coil current M B Braking torque n Speedt 2Normal brake reaction time1)Brake reaction to cut-off in the AC circuit 2)Brake reaction to cut-off in the DC and AC circuitst t t I S M B n 1)2)t 2t 2I SM Bnttt→ Sec.10001240ADE Fig. 5: Principles of cut-off in the DC and AC circuits Particularly quiet Particularly quiet brake motors are demanded in many applications in the power range up to approx. 5.5 kW in order to reduce noise pollution. SEW satisfies these conditions as standard in all brake motors up to size 132S by means of appropriate design features, without affecting the partic-ular dynamic properties of the brake system.Particularly safe The excitation power needed for the holding function may be too small in the event of a power fail-ure or especially severe voltage dips. The brake is applied for reasons of safety. A monitoring sys-tem ensures that the accelerator coil is reactivated when the voltage returns, thereby releasing the brake.AC M 3TS BS V11.7Working air gap with SEW brakes 1) Double disc brake Motor size Brake type Working air gap (mm)New setting Readjust at 6371/808090/100100B03BMG05, BC05BMG1, BC05BMG2, BC2BMG4, BC2min. 0.25max. 0.6112/132S 132M/160M 160L/180200/225BMG8BM15BM30BM31min. 0.3max. 1.2180200/225BM321)BM621)min. 0.4max. 1.2。